Hygrometric device



Patented Dec. 19,1922;

rnnnnnrc'r. BAHNSON, or WIlNSfION-SALEM, NORTH CAROLINA,

HYGROMETRIC nnv crli Application filed August 13, 1918. Serial No.249,697.

To all whom it may concern:

Be it known that I, Fnnnnnro F. BAHnsoiI,

' a citizen of the United States, residing at Winston-Salem, in thecounty of Fgrsyth and- State of North Carolina, have invented certainnew and useful Improvements in HygrometricDevices, of which thefollowing 1s a specification.

' This invention relates to improvements in the automatic control ofhumidifiers so that the relative humidity of-the air may be maintainedat any desired point. Heretofore humidity regulation has been. dependenton controlling devices which afford-practically no intermediate stepsbetween full' 9 operation of the humidifiers and entire stoppage oftheirevaporative effort. It is obvious that the efiect of such control wouldinevitably be such as to cause a saw tooth record on a recordinghygrometer.

his the particular object of this invention to provide controlling meansactuated by the relative humidity of the air, whereby the evaporativeeffort of a humidifier is auto-' matically varied in amount inproportion to the requirements to be met. The desired re- ;sult' isaccomplished by using avalve with a variable opening, the amplitude ofsuch opening being. controlled positively and directly by the effect ofthe moisture content I of the air 'ona specially designed hygrometricstrip.

This control is peculiarly adaptable to humidifiers-of the typedisclosed "in my Patent 1,267,166, and while that type is used in thisdisclosure for illustration, I'do not limit myself to that particularapplication, 'as this control may-be applied to any humidifying devicewhose humidifying action propormade without departing from the spiritand scope of the invention.

That the, construction and operation of the device may be understood,reference is had to the accompanying drawings in which the samereference numbers always indicate the same parts.

Fig. .1 is an elevatlon bf a device embodyin the invention;

I i v ig'.- 2 is a sectiomshowing the principal thereof on a"slightlylarger scale; and

' Fig. 3 is an elevation of a 'hygrometrically responsive elementforming the principal part of this invention.

The chief parts of the control are strip 10,

lever 16 which is held in position upon a fulcrum 16' by spring 15 inspring case 14,

whichiin turn is held in a'clamp 14 and V valve 25 operated by lever 16through valve stem 17 1n any suitable manner.

10 1s a long thin strip made preferably of one or more pieces sawedacross the grain from the end of a board of specially selected wood. Byselection ofwood to get substantially radial section I obtain a largetotal change of length in the strip'for varying rel ative humidities.Other material than wood may be used, and in specialapplications thestrlp may be made of the same material as that worked in the room whosehumidity it is desired to control.

7 Accuracy of control is accomplished by proper selection of materialfor strip 10, the degree of sensitiveness being determined by the lengthof strip 10. In practice I'usera strip less than 1% of whose totalavailable change of length will move valve 25 from tight closure to fullopening. It will be noted that lever 16 is so proportioned and arrangedthat any motion of strip 10 is multiplied on valve stem 17. As shown,the m0- tion of valve stem 17 is about double that of strip 10, but thisratio may be changed as desired.

The action of the control is as follows: Water is admitted from anyconvenient source through pipe 21 andhand operated valve 22 to chamber19 in which is located strainer 20. When strip 10 is dry from lowhumidity, valve 25 is open, the water passes tp'fchamber 18 from whichit is conducted to I found by experiment that strip 10 soon assumes sucha condition that valve 25 has a practically constant openin just enoughwater being permitted. to ho d the relative humidity of-the room at thedesired point In other-words, with constant conditions, valve 25 isautomatically held at the proper degree of opening to supply just enoughwater so that the evaporation of water by the humidifierexactlycompensates for the removal of moisture from the air in the room byleakage through walls' or openings or by absorption of such water by.dry materials. The construction of: strip lO is such that changes ofair condition readily and quickly cause change in its length. This makesmy control very quick acting.

It should be noted that the valve defines a steep cone and that thevalve seat is correspondingly sharp-angled. While the range of movementof the valve stem bewithin a Very small range of variations of therelative humidity. H

To avoid packing friction on the valve stem, I make valve stem 17 inj'two pieces,

- which, when screwed together, clamp between them the center. offlexible diaphragm 27,

ment by valve stem 17 along its axis, keepiqg it centeredin the valve,and at the same ti e chamber 18 is rendered water tight.

Adjusting screw 13 is provided to permit setting the control for anyrelative hu midity desired by changing the distance through which strip10 must expand in order to close valve 25.

Should therelative humidity fall very low, strip 10 simply contracts,and remains loose in guides 11. Ifthe relative humidity rises beyond thepoint at which stri 10 v 5 closes valve 25, further expansion of strlp10 simply pushes down lever 16 against the tension of spring 15, awayfrom fulcrum, 16, into a space provided for such movement by a deep slot16". in supporting block 23. If it is desired to flush out valve 25,chamber 18, or other parts ofthe feed system, the

end of lever 16- opposite the valve stem is pulled down. The attachmentof spring 15 "thus-becomes the fulcrum, the other end of lever 16 rises,"and, with it valve stem 17 opening valve 25 to the limit imposed bydiaphragm 27 striking the central shoulder of cap '28. 'The controlshould always be so placed whether on my humidifier or any other, ormounted at a distance, that it is surrounded by air in the condition ofthe average of the room and since the accuracy of any hygrometer isdependent upon active circulation of air over or around it, this controlshould, wherever fans are in operation, be placed in the air currentprov show that this control gives a remarkably smooth and uniform recordon a recording hygrometer placed in the. room controlled by myinvention. Various changes may be' made withinthe scope of theinvention.

which is'held at its outer edge by cap '28. This constructionpermits'freedom of move- 3 I claim 1. A hygrometric device consisting ofa pluarilty of thin strips of relatively stifi materialadapted to expandlengthwise under the effect of moisture and a guide .frame for looselysupportingthe strips in series.

2.- A hygrometric device consisting of a I I plurality of thin strips ofrelatively stifi material adapted to expand lengthwise under the effectof moisture, a guide frame for loosely supporting the strips in seriesand a movable abutment at one end of the guide for adjustablypositioning one end of the series.

-3. A hygrometric device consisting of a plurality of thin strips ofwood cut acrossthe grainand aguide frame for loosely sup-f porting saidstrips in series.

In testimony whereof, I aflix my signature.

FREDERIC F. BAHNSON.

